Security aspects in cloud based condition monitoring of machine tools

In the modern competitive environments companies must have rapid production systems that are able to deliver parts that satisfy highest quality standards. Companies have also an increased need for advanced machines equipped with the latest technologies in maintenance to avoid any reduction or interruption of production. Eminent therefore is the need to monitor the health status of the manufacturing equipment in real time and thus try to develop diagnostic technologies for machine tools. This paper lays the foundation for the creation of a safe remote monitoring system for machine tools using a Cloud environment for communication between the customer and the maintenance service company. Cloud technology provides a convenient means for accessing maintenance data anywhere in the world accessible through simple devices such as PC, tablets or smartphones. In this context the safety aspects of a Cloud system for remote monitoring of machine tools becomes crucial and is, thus the focus of this pape

Online on-board optimization of cutting parameter for energy efficient CNC milling

Energy efficiency is one of the main drivers for achieving sustainable manufacturing. Advances in machine tool design have reduced the energy consumption of such equipment, but still machine tools remain one of the most energy demanding equipment in a workshop. This study presents a novel approach aimed to improve the energy efficiency of machine tools through the online optimization of cutting conditions. The study is based on an industrial CNC controller with smart algorithms optimizing the cutting parameters to reduce the overall machining time while at the same time minimizing the peak energy consumption

Practical security aspects of the internet of things

Industry 4.0 and with that the Internet of Things (IoT) are expected to revolutionize the industrial world. The vast amount of interconnected devices bear the great opportunity to collect valuable information for advancing decision making in management and technology to improve through-life management of a product. Cyber-physical systems and the Internet of Services will revolutionize our current world through fully interconnected communication where information and services are becoming ubiquitous. The availability of information across a system of systems can be very powerful when utilized properly and harnessed adequately. The vast network of small, power-sensitive and often deeply embedded devices that are streaming potentially commercially sensitive data over long periods of time poses an entirely different type of threat than known from the conventional PC world. Adequate and sensible measures need to be taken right at the design stage of IoT devices in order to take best advantage of Industry 4.0 technology. This chapter introduces a set of key security issues related to the implementation of IoT in an industrial mechanical engineering context. A real-world example concerning remote maintenance of CNC machine tools illustrates the different threat scenarios related to IoT in practice. The paper touches on Big Data and Cloud Manufacturing but will remain focused on improving security at the Edge of IoT, i.e. where data is collected, transmitted and eventually transferred back to the physical actuators. The aim of this chapter is to introduce a generic overview of real-world IoT security issues as well as giving a deeper technical example-supported insight into practical considerations for designing IoT systems for practical use in business

Gear hobbing simulation and investigation of the technological parameters involved

Every high performance gear transmission module is composed of involute gears. External involute gears can be manufactured with a series of methods, the most widely applied of which being gear hobbing. The prediction of the quality of the produced gear and the determination of the cutting forces involved are of great importance. The present thesis introduces a novel simulation code called HOB3D that simulates the process of gear hobbing. This code can simulate the complex movements involved in gear hobbing with the best available accuracy, which is achieved by embedding the developed algorithm in a commercial CAD environment. The simulation code calculates the solid gap and non-deformed chip geometries. The latter where used to calculate the total cutting forces as well as the cutting forces in every cutting edge involved in the cutting process using Kienzle Victors’ equations. These equations predict the cutting forces in relation to the non-deformed chip geometry dimensions in the rake face of the cutter. The results of the model have been verified either with the use of analytic equations and experimental results, in the case of the profile of the produced gear gap, or with the use of experimental results found in the references, regarding the cutting forces. HOB3D is also equipped with a fully functional user friendly graphical user interface where the user can enter the simulation data, keep track of the simulation course, view and analyze the results. Moreover, a finite element program was used to simulate the flow of the chip in the confined space of a gear gap, as well as the determination of the developed cutting forces. Appropriate pre-processors were developed in order to prepare the data taken from HOB3D for an easier and error proof insertion in the finite element program selected. In order to verify the results of the model, the trajectories that the cutter forms where compared to the ones created by ΗΟΒ3D. The cutting forces that were calculated were also verified with the HOB3D corresponding results. Finally, the effect of the different machining data on the resulting cutting forces was studied. Parameters like the module and the number of teeth of the produced gear, the number of hob columns and origins, and the axial feed was studied with respect to the maximum and minimum developed cutting force components.Η κατασκευή οδοντώσεων συνθέτει διεθνώς μια από τις πλέον σημαντικές παραγωγικές διαδικασίες, με υψηλό τεχνολογικό και οικονομικό ενδιαφέρον. Είναι χαρακτηριστικό ότι ο αριθμός των παραγόμενων οδοντωτών τροχών υψηλής ακρίβειας ξεπερνά τα ένα δισεκατομμύριο τεμάχια ετησίως. Ως εκ τούτου, είναι φανερό ότι η βελτιστοποίηση του παραγωγικού εξοπλισμού, των διαδικασιών και της ποιότητας των τελικών προϊόντων στις κατεργασίες οδοντώσεων συνθέτουν θέματα ερευνητικής αιχμής. Η συντριπτική πλειοψηφία των τελικών προϊόντων οδοντώσεων παράγεται μέσω της κατεργασίας του φραιζαρίσματος με κύλιση οδοντώσεων (gear hobbing). Η σύνθετη κινηματική της εν λόγω κατεργασίας, αλλά και η πολύπλοκη γεωμετρία των κοπτήρων, αποτελούν δύο μόνο από τα σημαντικά προβλήματα που ανακύπτουν, μέσω των προσπαθειών βελτιστοποίησής της. Το αντικείμενο της παρούσας διατριβής είναι η ανάπτυξη ενός ολοκληρωμένου μοντέλου (HOB3D) με τη βοήθεια ενός συστήματος CAD, το οποίο θα είναι σε θέση να προσομοιώσει την κατεργασία οδοντώσεων με φραιζάρισμα με κύλιση. Για την καλύτερη υλοποίηση του στόχου χρησιμοποιήθηκε η ακρίβεια ενός εμπορικού πακέτου CAD για τη μοντελοποίηση της γεωμετρίας του κοπτικού εργαλείου καθώς και για τη μοντελοποίηση της σύνθετης κινηματικής της κατεργασίας. Έτσι τα παραγόμενα αποτελέσματα του μοντέλου έχουν τη μέγιστη δυνατή ακρίβεια και περιλαμβάνουν τη τρισδιάστατη γεωμετρία του τελικού τροχού και όλων των ενδιάμεσων απαραμόρφωτων αποβλίττων και τις αναπτυσσόμενες δυνάμεις κοπής. Τα αποτελέσματα του μοντέλου επιβεβαιώθηκαν επίσης, είτε με αναλυτικές σχέσεις και πειραματικά δεδομένα στη περίπτωση της γεωμετρίας της παραγόμενης αυλάκωσης, είτε με αποτελέσματα πειραμάτων που αντλήθηκαν από τη βιβλιογραφία και αφορούν τις δυνάμεις κοπής, τόσο σε κάθε ένα κοπτικό δόντι, όσο και συνολικά σε όλο το κοπτικό εργαλείο. Το μοντέλο εξοπλίστηκε με ένα πλήρως λειτουργικό περιβάλλον μέσα από το οποίο ο χρήστης μπορεί να εκπονήσει προσομοιώσεις καθώς και να αναλύσει τα αποτελέσματα των προσομοιώσεων αυτών. Στη συνέχεια και προκειμένου να συγκριθεί το μοντέλο που αναπτύχθηκε με αντίστοιχα γενικότερα μοντέλα που χρησιμοποιούν πεπερασμένα στοιχεία, αναπτύχθηκε αντίστοιχο μοντέλο πεπερασμένων στοιχείων με τη βοήθεια του λογισμικού Deform. Το μοντέλο χρησιμοποιήθηκε για την ανάλυση της ροής του αποβλίττου μέσα στο αυλάκι καθώς και, επιπλέον των ανωτέρω, για επιβεβαίωση των υπολογισμένων με το λογισμικό HOB3D απαραμόρφωτων αποβλίττων και των αναπτυσσομένων δυνάμεων κοπής. Για την κατασκευή του μοντέλου πεπερασμένων στοιχείων χρησιμοποιήθηκαν δεδομένα από το μοντέλο προσομοίωσης με χρήση συστήματος CAD για τους συμμετέχοντες παράγοντες της κοπής (εργαλείο, τεμάχιο) ενώ τα αποτελέσματά του επιβεβαιώθηκαν με αντίστοιχα αποτελέσματα από τη διεθνή βιβλιογραφία. Τέλος, έγινε διερεύνηση των βέλτιστων συνθηκών κατεργασίας ανά περίπτωση, με βάση το μοντέλο που αναπτύχθηκ

Parametric Modeling of Curvic Couplings and Analysis of the Effect of Coupling Geometry on Contact Stresses in High-Speed Rotation Applications

Curvic couplings are used in applications demanding high positional accuracy and high torque transmission; therefore, improving their design and enhancing their load-carrying capacity is crucial. This study introduced the kinematic model Curvic3D, which was developed to produce the accurate geometry of both members of a curvic coupling using a CAD system. The model enabled the complete parametrization and customization of the coupling design using important geometric parameters. The couplings produced using Curvic3D were then imported into a finite element analysis model also developed as part of this study. A detailed analysis of the stresses developed on the teeth of the concave and convex parts provided information about the behavior of the coupling under different loading conditions. Finally, a series of geometric parameters, such as the number of teeth, the number of half pitches, the root fillet radius, and gable angle were examined as to their influence on the load-carrying capacity of the curvic coupling. The study concluded that all the examined parameters have a significant effect on the tooth flank and root area stresses

3D-FEM Approach of AISI-52100 Hard Turning: Modelling of Cutting Forces and Cutting Condition Optimization

In the present study, a 3D finite element (FE) model for machining AISI-52100 steel was proposed, with respect to three levels of cutting speed (100 m/min, 150 m/min and 200 m/min), feed (0.08 mm/rev, 0.11 mm/rev and 0.14 mm/rev), depth of cut (0.20 mm, 0.30 mm and 0.40 mm) and tool nose radius (0.80 mm, 1.20 mm and 1.60 mm). Nine simulation tests were performed according to cutting conditions that were used in experimental studies, in order to verify the accuracy of the model. Next, the FE model was utilized to carry out thirty new simulation runs, with cutting conditions derived from the implementation of the central composite design (CCD). Additionally, a mathematical model was established for prediction purposes, whereas the relationship between the applied cutting parameters and their influence on the resultant cutting force was investigated with the aid of statistical methodologies such as the response surface methodology (RSM) and the analysis of variance (ANOVA). The comparison between the numerical and the statistical model revealed an increased level of correlation, superseding 90% in many tests. Specifically, the relative error varied between −7.9% and 11.3%. Lastly, an optimization process was performed to find the optimal cutting conditions for minimizing the resultant machining force, as per the standardized tool nose radius value

A cloud-based, knowledge-enriched framework for increasing machining efficiency based on machine tool monitoring

The ever-increasing complexity in manufacturing systems caused by the fluctuating customer demands has highly affected the contemporary shop-floors. The selection of the appropriate cutting parameters is becoming more and more challenging due to the increasing complexity of products. Until now, the knowledge of the machine operators concerning the modification of the machining parameters and the monitoring information is not sufficiently exploited by the optimization systems. Web and Cloud technologies together with wireless sensor networks are required to capture the shop-floor data and enable the ubiquitous access from multiple IT tools. For addressing these challenges, this research work proposes a Cloud-based, knowledge-enriched framework for machining efficiency based on machine tool monitoring. More precisely, it focuses on the optimization of the machining parameters and moves through an event-driven optimization algorithm, utilizing the existing machining knowledge captured by the monitoring system. Based on the features of a new part, a similarity mechanism retrieves the cutting parameters of successfully executed past parts that have been machined. Afterwards, the optimization module, using event-driven function blocks, adapts these parameters to efficiently optimize the moves and the cutting parameters. The monitoring system uses a wireless sensor network and a human operator input via mobile devices. A case study from the mould-making industry is used for validating the proposed framework

A novel CAD-based simulation model for manufacturing of spiral bevel gears by face milling

Summarization: Bevel gears are employed in the transmission of motion and torque via non-parallel shafts. When higher strength and lower noise is the objective, spiral bevel gears are used because of their higher tooth contact ratio. Face milling and face hobbing are among the most significant operations for the machining of hypoid and spiral bevel gears due to their high productivity. Although the optimization of these processes is crucial for the production of high-quality gears and the minimization of the total manufacturing cost, there are not many studies reported in this research area, owing to the high complexity of process kinematics. Furthermore, several kinematic variations of the two methods are applied in industry and their results depend highly on the cutting tool geometry. A novel simulation model integrated into a commercial CAD platform has been developed. The model achieves the 3D kinematic simulation of both face milling and face hobbing processes, generating the undeformed solid chip geometry as well as the simulated tooth solid geometry of a spiral bevel gear pinion and a spiral bevel gear wheel as an output. The simulation approach has two main purposes. First, is the optimization of the process through the investigation of the effect of cutting parameters on the quality of the obtained solid tooth flank geometry and second, is the calculation of cutting forces with the use of the obtained solid chip geometries. Aiming towards the validation of the model, the resulted tooth flank geometry is compared with the theoretical tooth exported from a well-established commercial gear calculation and design software and it is verified by means of a novel validation algorithm, also developed as part of this study. This paper focuses on the presentation of the kinematic simulation methodology and the simulation results for the face milling process. An insight into the validation model is provided and validation results are also presented. Finally, a sample investigation of the effect of generating feed rate on the produced gear geometry is conducted with the use of both algorithms.Presented on: CIRP Journal of Manufacturing Science and Technolog

3-Dimensional kinematics simulation of face milling

Summarization: Face milling is currently the most effective and productive manufacturing method for roughing and finishing large surfaces of metallic parts. Milling data, such as surface topomorphy, surface roughness, non-deformed chip dimensions, cutting force components and dynamic cutting behavior, are very helpful, especially if they can be accurately produced by means of a simulation program. This paper presents a novel simulation model which has been developed and embedded in a commercial CAD environment. The model simulates the true tool kinematics using the exact geometry of the cutting tool thus accurately forecasting the resulting roughness. The accuracy of the simulation model has been thoroughly verified, with the aid of a wide variety of cutting experiments. The proposed model has proved to be suitable for determining optimal cutting conditions for face milling. The software can be easily integrated into various CAD–CAM systems.Presented on: Measuremen